build: add --node-snapshot-main configure option

This adds a --build-snapshot runtime option which is currently only supported by the node_mksnapshot binary, and a --node-snapshot-main configure option that makes use it to run a custom script when building the embedded snapshot. The idea is to have this experimental feature in core as a configure-time feature for now, and investigate the renaming V8 bugs before we make it available to more users via making it a runtime option. PR-URL: #42466 Reviewed-By: Darshan Sen <[email protected]> Reviewed-By: Mohammed Keyvanzadeh <[email protected]> Reviewed-By: Khaidi Chu <[email protected]> Reviewed-By: Chengzhong Wu <[email protected]>
nodejs · May 31, 2022 · ce5e484 · ce5e484
1 parent 8970167
commit ce5e484
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Showing 12 changed files with 365 additions and 36 deletions.
diff --git a/configure.py b/configure.py
@@ -792,6 +792,13 @@
     default=False,
     help='node will load builtin modules from disk instead of from binary')
 
+parser.add_argument('--node-snapshot-main',
+    action='store',
+    dest='node_snapshot_main',
+    default=None,
+    help='Run a file when building the embedded snapshot. Currently ' +
+         'experimental.')
+
 # Create compile_commands.json in out/Debug and out/Release.
 parser.add_argument('-C',
     action='store_true',
@@ -1219,6 +1226,18 @@ def configure_node(o):
 
   o['variables']['want_separate_host_toolset'] = int(cross_compiling)
 
+  if options.node_snapshot_main is not None:
+    if options.shared:
+      # This should be possible to fix, but we will need to refactor the
+      # libnode target to avoid building it twice.
+      error('--node-snapshot-main is incompatible with --shared')
+    if options.without_node_snapshot:
+      error('--node-snapshot-main is incompatible with ' +
+            '--without-node-snapshot')
+    if cross_compiling:
+      error('--node-snapshot-main is incompatible with cross compilation')
+    o['variables']['node_snapshot_main'] = options.node_snapshot_main
+
   if options.without_node_snapshot or options.node_builtin_modules_path:
     o['variables']['node_use_node_snapshot'] = 'false'
   else:

diff --git a/lib/internal/bootstrap/pre_execution.js b/lib/internal/bootstrap/pre_execution.js
@@ -26,7 +26,8 @@ const { Buffer } = require('buffer');
 const { ERR_MANIFEST_ASSERT_INTEGRITY } = require('internal/errors').codes;
 const assert = require('internal/assert');
 
-function prepareMainThreadExecution(expandArgv1 = false) {
+function prepareMainThreadExecution(expandArgv1 = false,
+                                    initialzeModules = true) {
   refreshRuntimeOptions();
 
   // TODO(joyeecheung): this is also necessary for workers when they deserialize
@@ -80,9 +81,13 @@ function prepareMainThreadExecution(expandArgv1 = false) {
   initializeSourceMapsHandlers();
   initializeDeprecations();
   initializeWASI();
+
+  if (!initialzeModules) {
+    return;
+  }
+
   initializeCJSLoader();
   initializeESMLoader();
-
   const CJSLoader = require('internal/modules/cjs/loader');
   assert(!CJSLoader.hasLoadedAnyUserCJSModule);
   loadPreloadModules();
@@ -101,7 +106,8 @@ function patchProcessObject(expandArgv1) {
 
   ObjectDefineProperty(process, 'argv0', {
     enumerable: true,
-    configurable: false,
+    // Only set it to true during snapshot building.
+    configurable: getOptionValue('--build-snapshot'),
     value: process.argv[0]
   });
   process.argv[0] = process.execPath;

diff --git a/lib/internal/main/mksnapshot.js b/lib/internal/main/mksnapshot.js
@@ -0,0 +1,142 @@
+'use strict';
+
+const {
+  Error,
+  SafeSet,
+  SafeArrayIterator
+} = primordials;
+
+const binding = internalBinding('mksnapshot');
+const { NativeModule } = require('internal/bootstrap/loaders');
+const {
+  compileSnapshotMain,
+} = binding;
+
+const {
+  getOptionValue
+} = require('internal/options');
+
+const {
+  readFileSync
+} = require('fs');
+
+const supportedModules = new SafeSet(new SafeArrayIterator([
+  // '_http_agent',
+  // '_http_client',
+  // '_http_common',
+  // '_http_incoming',
+  // '_http_outgoing',
+  // '_http_server',
+  '_stream_duplex',
+  '_stream_passthrough',
+  '_stream_readable',
+  '_stream_transform',
+  '_stream_wrap',
+  '_stream_writable',
+  // '_tls_common',
+  // '_tls_wrap',
+  'assert',
+  'assert/strict',
+  // 'async_hooks',
+  'buffer',
+  // 'child_process',
+  // 'cluster',
+  'console',
+  'constants',
+  'crypto',
+  // 'dgram',
+  // 'diagnostics_channel',
+  // 'dns',
+  // 'dns/promises',
+  // 'domain',
+  'events',
+  'fs',
+  'fs/promises',
+  // 'http',
+  // 'http2',
+  // 'https',
+  // 'inspector',
+  // 'module',
+  // 'net',
+  'os',
+  'path',
+  'path/posix',
+  'path/win32',
+  // 'perf_hooks',
+  'process',
+  'punycode',
+  'querystring',
+  // 'readline',
+  // 'repl',
+  'stream',
+  'stream/promises',
+  'string_decoder',
+  'sys',
+  'timers',
+  'timers/promises',
+  // 'tls',
+  // 'trace_events',
+  // 'tty',
+  'url',
+  'util',
+  'util/types',
+  'v8',
+  // 'vm',
+  // 'worker_threads',
+  // 'zlib',
+]));
+
+const warnedModules = new SafeSet();
+function supportedInUserSnapshot(id) {
+  return supportedModules.has(id);
+}
+
+function requireForUserSnapshot(id) {
+  if (!NativeModule.canBeRequiredByUsers(id)) {
+    // eslint-disable-next-line no-restricted-syntax
+    const err = new Error(
+      `Cannot find module '${id}'. `
+    );
+    err.code = 'MODULE_NOT_FOUND';
+    throw err;
+  }
+  if (!supportedInUserSnapshot(id)) {
+    if (!warnedModules.has(id)) {
+      process.emitWarning(
+        `built-in module ${id} is not yet supported in user snapshots`);
+      warnedModules.add(id);
+    }
+  }
+
+  return require(id);
+}
+
+function main() {
+  const {
+    prepareMainThreadExecution
+  } = require('internal/bootstrap/pre_execution');
+
+  prepareMainThreadExecution(true, false);
+  process.once('beforeExit', function runCleanups() {
+    for (const cleanup of binding.cleanups) {
+      cleanup();
+    }
+  });
+
+  const file = process.argv[1];
+  const path = require('path');
+  const filename = path.resolve(file);
+  const dirname = path.dirname(filename);
+  const source = readFileSync(file, 'utf-8');
+  const snapshotMainFunction = compileSnapshotMain(filename, source);
+
+  if (getOptionValue('--inspect-brk')) {
+    internalBinding('inspector').callAndPauseOnStart(
+      snapshotMainFunction, undefined,
+      requireForUserSnapshot, filename, dirname);
+  } else {
+    snapshotMainFunction(requireForUserSnapshot, filename, dirname);
+  }
+}
+
+main();
diff --git a/node.gyp b/node.gyp
@@ -7,6 +7,7 @@
     'node_use_dtrace%': 'false',
     'node_use_etw%': 'false',
     'node_no_browser_globals%': 'false',
+    'node_snapshot_main%': '',
     'node_use_node_snapshot%': 'false',
     'node_use_v8_platform%': 'true',
     'node_use_bundled_v8%': 'true',
@@ -315,23 +316,47 @@
           'dependencies': [
             'node_mksnapshot',
           ],
-          'actions': [
-            {
-              'action_name': 'node_mksnapshot',
-              'process_outputs_as_sources': 1,
-              'inputs': [
-                '<(node_mksnapshot_exec)',
-              ],
-              'outputs': [
-                '<(SHARED_INTERMEDIATE_DIR)/node_snapshot.cc',
+          'conditions': [
+            ['node_snapshot_main!=""', {
+              'actions': [
+                {
+                  'action_name': 'node_mksnapshot',
+                  'process_outputs_as_sources': 1,
+                  'inputs': [
+                    '<(node_mksnapshot_exec)',
+                    '<(node_snapshot_main)',
+                  ],
+                  'outputs': [
+                    '<(SHARED_INTERMEDIATE_DIR)/node_snapshot.cc',
+                  ],
+                  'action': [
+                    '<(node_mksnapshot_exec)',
+                    '--build-snapshot',
+                    '<(node_snapshot_main)',
+                    '<@(_outputs)',
+                  ],
+                },
               ],
-              'action': [
-                '<@(_inputs)',
-                '<@(_outputs)',
+            }, {
+              'actions': [
+                {
+                  'action_name': 'node_mksnapshot',
+                  'process_outputs_as_sources': 1,
+                  'inputs': [
+                    '<(node_mksnapshot_exec)',
+                  ],
+                  'outputs': [
+                    '<(SHARED_INTERMEDIATE_DIR)/node_snapshot.cc',
+                  ],
+                  'action': [
+                    '<@(_inputs)',
+                    '<@(_outputs)',
+                  ],
+                },
               ],
-            },
+            }],
           ],
-        }, {
+          }, {
           'sources': [
             'src/node_snapshot_stub.cc'
           ],

diff --git a/src/node.cc b/src/node.cc
@@ -486,6 +486,10 @@ MaybeLocal<Value> StartExecution(Environment* env, StartExecutionCallback cb) {
     return StartExecution(env, "internal/main/inspect");
   }
 
+  if (per_process::cli_options->build_snapshot) {
+    return StartExecution(env, "internal/main/mksnapshot");
+  }
+
   if (per_process::cli_options->print_help) {
     return StartExecution(env, "internal/main/print_help");
   }
@@ -1144,6 +1148,12 @@ int Start(int argc, char** argv) {
     return result.exit_code;
   }
 
+  if (per_process::cli_options->build_snapshot) {
+    fprintf(stderr,
+            "--build-snapshot is not yet supported in the node binary\n");
+    return 1;
+  }
+
   {
     bool use_node_snapshot =
         per_process::cli_options->per_isolate->node_snapshot;

diff --git a/src/node_binding.cc b/src/node_binding.cc
@@ -59,6 +59,7 @@
   V(js_udp_wrap)                                                               \
   V(messaging)                                                                 \
   V(module_wrap)                                                               \
+  V(mksnapshot)                                                                \
   V(native_module)                                                             \
   V(options)                                                                   \
   V(os)                                                                        \

diff --git a/src/node_external_reference.h b/src/node_external_reference.h
@@ -66,6 +66,7 @@ class ExternalReferenceRegistry {
   V(handle_wrap)                                                               \
   V(heap_utils)                                                                \
   V(messaging)                                                                 \
+  V(mksnapshot)                                                                \
   V(native_module)                                                             \
   V(options)                                                                   \
   V(os)                                                                        \

diff --git a/src/node_options.cc b/src/node_options.cc
@@ -716,6 +716,11 @@ PerProcessOptionsParser::PerProcessOptionsParser(
             "disable Object.prototype.__proto__",
             &PerProcessOptions::disable_proto,
             kAllowedInEnvironment);
+  AddOption("--build-snapshot",
+            "Generate a snapshot blob when the process exits."
+            "Currently only supported in the node_mksnapshot binary.",
+            &PerProcessOptions::build_snapshot,
+            kDisallowedInEnvironment);
 
   // 12.x renamed this inadvertently, so alias it for consistency within the
   // release line, while using the original name for consistency with older

diff --git a/src/node_options.h b/src/node_options.h
@@ -224,6 +224,7 @@ class PerProcessOptions : public Options {
   bool zero_fill_all_buffers = false;
   bool debug_arraybuffer_allocations = false;
   std::string disable_proto;
+  bool build_snapshot;
 
   std::vector<std::string> security_reverts;
   bool print_bash_completion = false;